/*
 * jcmainct.c
 *
 * Copyright (C) 1994-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains the main buffer controller for compression.
 * The main buffer lies between the pre-processor and the JPEG
 * compressor proper; it holds downsampled data in the JPEG colorspace.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* Note: currently, there is no operating mode in which a full-image buffer
 * is needed at this step.  If there were, that mode could not be used with
 * "raw data" input, since this module is bypassed in that case.  However,
 * we've left the code here for possible use in special applications.
 */
#undef FULL_MAIN_BUFFER_SUPPORTED


/* Private buffer controller object */

typedef struct {
    struct jpeg_c_main_controller pub;/* public fields */

    JDIMENSION cur_iMCU_row;/* number of current iMCU row */
    JDIMENSION rowgroup_ctr;/* counts row groups received in iMCU row */
    boolean    suspended;   /* remember if we suspended output */
    J_BUF_MODE pass_mode;   /* current operating mode */

    /* If using just a strip buffer, this points to the entire set of buffers
     * (we allocate one for each component).  In the full-image case, this
     * points to the currently accessible strips of the virtual arrays.
     */
    JSAMPARRAY buffer[MAX_COMPONENTS];

#ifdef FULL_MAIN_BUFFER_SUPPORTED
    /* If using full-image storage, this array holds pointers to virtual-array
     * control blocks for each component.  Unused if not full-image storage.
     */
    jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
#endif
} my_main_controller;

typedef my_main_controller * my_main_ptr;


/* Forward declarations */
METHODDEF void process_data_simple_main
JPP( ( j_compress_ptr cinfo, JSAMPARRAY input_buf,
       JDIMENSION * in_row_ctr, JDIMENSION in_rows_avail ) );
#ifdef FULL_MAIN_BUFFER_SUPPORTED
METHODDEF void process_data_buffer_main
JPP( ( j_compress_ptr cinfo, JSAMPARRAY input_buf,
       JDIMENSION * in_row_ctr, JDIMENSION in_rows_avail ) );
#endif


/*
 * Initialize for a processing pass.
 */

METHODDEF void
start_pass_main( j_compress_ptr cinfo, J_BUF_MODE pass_mode ) {
    my_main_ptr main = (my_main_ptr) cinfo->main;

    /* Do nothing in raw-data mode. */
    if ( cinfo->raw_data_in ) {
        return;
    }

    main->cur_iMCU_row = 0; /* initialize counters */
    main->rowgroup_ctr = 0;
    main->suspended = FALSE;
    main->pass_mode = pass_mode;/* save mode for use by process_data */

    switch ( pass_mode ) {
        case JBUF_PASS_THRU:
#ifdef FULL_MAIN_BUFFER_SUPPORTED
            if ( main->whole_image[0] != NULL ) {
                ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
            }
#endif
            main->pub.process_data = process_data_simple_main;
            break;
#ifdef FULL_MAIN_BUFFER_SUPPORTED
        case JBUF_SAVE_SOURCE:
        case JBUF_CRANK_DEST:
        case JBUF_SAVE_AND_PASS:
            if ( main->whole_image[0] == NULL ) {
                ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
            }
            main->pub.process_data = process_data_buffer_main;
            break;
#endif
        default:
            ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
            break;
    }
}


/*
 * Process some data.
 * This routine handles the simple pass-through mode,
 * where we have only a strip buffer.
 */

METHODDEF void
process_data_simple_main( j_compress_ptr cinfo,
                          JSAMPARRAY input_buf, JDIMENSION * in_row_ctr,
                          JDIMENSION in_rows_avail ) {
    my_main_ptr main = (my_main_ptr) cinfo->main;

    while ( main->cur_iMCU_row < cinfo->total_iMCU_rows ) {
        /* Read input data if we haven't filled the main buffer yet */
        if ( main->rowgroup_ctr < DCTSIZE ) {
            ( *cinfo->prep->pre_process_data )( cinfo,
                                                input_buf, in_row_ctr, in_rows_avail,
                                                main->buffer, &main->rowgroup_ctr,
                                                (JDIMENSION) DCTSIZE );
        }

        /* If we don't have a full iMCU row buffered, return to application for
         * more data.  Note that preprocessor will always pad to fill the iMCU row
         * at the bottom of the image.
         */
        if ( main->rowgroup_ctr != DCTSIZE ) {
            return;
        }

        /* Send the completed row to the compressor */
        if ( !( *cinfo->coef->compress_data )( cinfo, main->buffer ) ) {
            /* If compressor did not consume the whole row, then we must need to
             * suspend processing and return to the application.  In this situation
             * we pretend we didn't yet consume the last input row; otherwise, if
             * it happened to be the last row of the image, the application would
             * think we were done.
             */
            if ( !main->suspended ) {
                ( *in_row_ctr )--;
                main->suspended = TRUE;
            }
            return;
        }
        /* We did finish the row.  Undo our little suspension hack if a previous
         * call suspended; then mark the main buffer empty.
         */
        if ( main->suspended ) {
            ( *in_row_ctr )++;
            main->suspended = FALSE;
        }
        main->rowgroup_ctr = 0;
        main->cur_iMCU_row++;
    }
}


#ifdef FULL_MAIN_BUFFER_SUPPORTED

/*
 * Process some data.
 * This routine handles all of the modes that use a full-size buffer.
 */

METHODDEF void
process_data_buffer_main( j_compress_ptr cinfo,
                          JSAMPARRAY input_buf, JDIMENSION * in_row_ctr,
                          JDIMENSION in_rows_avail ) {
    my_main_ptr main = (my_main_ptr) cinfo->main;
    int ci;
    jpeg_component_info * compptr;
    boolean writing = ( main->pass_mode != JBUF_CRANK_DEST );

    while ( main->cur_iMCU_row < cinfo->total_iMCU_rows ) {
        /* Realign the virtual buffers if at the start of an iMCU row. */
        if ( main->rowgroup_ctr == 0 ) {
            for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
                  ci++, compptr++ ) {
                main->buffer[ci] = ( *cinfo->mem->access_virt_sarray )
                                   ( (j_common_ptr) cinfo, main->whole_image[ci],
                                    main->cur_iMCU_row * ( compptr->v_samp_factor * DCTSIZE ),
                                    (JDIMENSION) ( compptr->v_samp_factor * DCTSIZE ), writing );
            }
            /* In a read pass, pretend we just read some source data. */
            if ( !writing ) {
                *in_row_ctr += cinfo->max_v_samp_factor * DCTSIZE;
                main->rowgroup_ctr = DCTSIZE;
            }
        }

        /* If a write pass, read input data until the current iMCU row is full. */
        /* Note: preprocessor will pad if necessary to fill the last iMCU row. */
        if ( writing ) {
            ( *cinfo->prep->pre_process_data )( cinfo,
                                                input_buf, in_row_ctr, in_rows_avail,
                                                main->buffer, &main->rowgroup_ctr,
                                                (JDIMENSION) DCTSIZE );
            /* Return to application if we need more data to fill the iMCU row. */
            if ( main->rowgroup_ctr < DCTSIZE ) {
                return;
            }
        }

        /* Emit data, unless this is a sink-only pass. */
        if ( main->pass_mode != JBUF_SAVE_SOURCE ) {
            if ( !( *cinfo->coef->compress_data )( cinfo, main->buffer ) ) {
                /* If compressor did not consume the whole row, then we must need to
                 * suspend processing and return to the application.  In this situation
                 * we pretend we didn't yet consume the last input row; otherwise, if
                 * it happened to be the last row of the image, the application would
                 * think we were done.
                 */
                if ( !main->suspended ) {
                    ( *in_row_ctr )--;
                    main->suspended = TRUE;
                }
                return;
            }
            /* We did finish the row.  Undo our little suspension hack if a previous
             * call suspended; then mark the main buffer empty.
             */
            if ( main->suspended ) {
                ( *in_row_ctr )++;
                main->suspended = FALSE;
            }
        }

        /* If get here, we are done with this iMCU row.  Mark buffer empty. */
        main->rowgroup_ctr = 0;
        main->cur_iMCU_row++;
    }
}

#endif /* FULL_MAIN_BUFFER_SUPPORTED */


/*
 * Initialize main buffer controller.
 */

GLOBAL void
jinit_c_main_controller( j_compress_ptr cinfo, boolean need_full_buffer ) {
    my_main_ptr main;
    int ci;
    jpeg_component_info * compptr;

    main = (my_main_ptr)
           ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
                                        SIZEOF( my_main_controller ) );
    cinfo->main = (struct jpeg_c_main_controller *) main;
    main->pub.start_pass = start_pass_main;

    /* We don't need to create a buffer in raw-data mode. */
    if ( cinfo->raw_data_in ) {
        return;
    }

    /* Create the buffer.  It holds downsampled data, so each component
     * may be of a different size.
     */
    if ( need_full_buffer ) {
#ifdef FULL_MAIN_BUFFER_SUPPORTED
        /* Allocate a full-image virtual array for each component */
        /* Note we pad the bottom to a multiple of the iMCU height */
        for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
              ci++, compptr++ ) {
            main->whole_image[ci] = ( *cinfo->mem->request_virt_sarray )
                                    ( (j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
                                     compptr->width_in_blocks * DCTSIZE,
                                     (JDIMENSION) jround_up( (long) compptr->height_in_blocks,
                                                            (long) compptr->v_samp_factor ) * DCTSIZE,
                                     (JDIMENSION) ( compptr->v_samp_factor * DCTSIZE ) );
        }
#else
        ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
#endif
    } else {
#ifdef FULL_MAIN_BUFFER_SUPPORTED
        main->whole_image[0] = NULL;/* flag for no virtual arrays */
#endif
        /* Allocate a strip buffer for each component */
        for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
              ci++, compptr++ ) {
            main->buffer[ci] = ( *cinfo->mem->alloc_sarray )
                               ( (j_common_ptr) cinfo, JPOOL_IMAGE,
                                compptr->width_in_blocks * DCTSIZE,
                                (JDIMENSION) ( compptr->v_samp_factor * DCTSIZE ) );
        }
    }
}
